The invention relates to a portable hand machine tool, particularly an angle grinder. A portable hand machine tool is known (EP-OS No. 152,564) in which a slide element is supported for transverse sliding along guide means in the housing and has an inclined surface acting on an axial flange surface of the spindle during the transverse sliding. The spindle is then slid axially relative to the drive shaft together with a screwed-on spindle nut so far that an axial slackening of the clamp nut then occurs, whereupon the clamp nut can be unscrewed fully by hand without the need for additional tools. It is thereby intended to permit an exchange of a tool, a grinding wheel of an angle grinder for example, without use of an additional tool so that the exchange can be effected rapidly and simply by hand. In this hand machine tool, an axial spring is inserted between the spindle and the drive shaft. The spring forces the spindle in the opposite direction into an initial position defined by an axial stop when the slide element is inoperative. When clamping a tool, in particular a grinding wheel, by screwing on and tightening the clamp nut, the grinding wheel becomes clamped between the clamp nut and the counterflange as a part of the drive shaft braced axially against the latter. An axial traction force then acts upon the spindle, and has to be braced by the drive shaft through the spring. As is known, the clamp nut tightens further spontaneously during the operation of the hand machine tool. It is therefore necessary for the spring to have an extraordinary rigidity in order to ensure this tightening and the firm seat of the clamp tool with certainty. If the spindle is to be slid axially relative to the drive shaft for slackening without using an additional tool and release of the clamp nut, by a transverse sliding of the slide element, then it is necessary for the inclined surface of the latter to exert an additional axial force which enables the slackening by compressing the axial spring. Sliding of the slide element, therefore, requires application of a considerable force, which makes the manipulation considerably more difficult and can generally actually be applied only with the assistance of additional auxiliary tools. It is also necessary for the operator to ensure that after a tool change, the slide element is first of all slid back into a "closed" position and its inclined surface therefore moves out of engagement with the spindle before the drive motor is switched on. If this is neglected and the drive motor is switched on while the inclined surface is still in engagement with the spindle, there is a danger of the motor being damaged and/or the inclined surface and the axial surface of the spindle, which it stresses, being ground away and damaged. The manipulation of the fastening device, particularly of the slide element, therefore demands particular attention by the operator. No automatic, possibly spring elastic, return possibility for the slide element is available here.